No you don't sand the base coat and on the "application" part of the paint's instructions (doesn't matter the manufacturer) it clearly says so.
"color sanding" is only used for single stage paints which, as the name suggests, only consist of a single type of paint. The paint has the proper materials in it to bring up the shine and protect the finish
"Wet sanding" is used on Dual Stage paints (u quessed it base and clear coat systems) in which the base is only applied in layers enough to achive "hiding". It has no properties to for gloss or to provide protection but provides the proper "substrate" for the Cleat Coat.
If you sand the base coat you'll have to re-apply more before being able to shoot the cleat coat over it.
After the cleat coat is applied then you wet sand.
Paint maching can be achived either by using the letter code found on the RPO Sticker some where on the car or by taking the car to any Auto Body supply store which sells auto paint. They have a really cool camera there that they bring out and put on a panel.
It takes a picture (or something) and they download that information to another machine inside the store and it tells them exactly what color that paint is and what to mix up to get it.
It takes alot to get a paint job without any orange peel, and after painting a few cars if that's the worse defect I have when I'm done (it can get worse) it's not a big thing cause you'll need to wetsand the finish anyway.
Check the
AutoBody Store forums and how-to's for more info